It will be seen that the number of persons employed under ground in mines amounts to 193,825, being nearly equal to an eighth of the total numbers employed in the cultivation of the surface. Of these by far the largest proportion; namely, 118,233, are returned as engaged in coal mines, and only 10,949 in iron mines. It must be remembered, however, that these two minerals run in close neighbourhood together, and are worked more or less constantly with reference to the extent of the demand, so that the same men are transferred from time to time to one or the other. At the period of the Census there was considerable depression in the iron trade, while it was taken just at the period when the larger coal-merchants throughout the kingdom were laying in their stocks, and when the carrying trade for sea-borne coal was most active. This will in some degree account for a greater' disproportion than might otherwise have been expected in these two branches. It should also be noticed that there are 31,173 persons returned under the general head of miners, who would most likely represent many usually employed in iron mines, but temporarily out of employ. The manufacture of iron from the raw material gives employment to nearly 30,000 persons.